Solar power generation currently comprises wiring a number of solar panels together to supply DC power to an inverter. The solar panels are generally connected in series such that the DC voltage generated is higher than the required AC voltage and an inverter converts this DC voltage into AC power at the required mains voltage.
For traditional inverters, the conversion efficiency is generally in the range of 92% to 96% and this value varies with the level of sunlight and voltage provided by the solar cells. Transformerless inverters can reach efficiencies as high as 98% at an optimal supply voltage and power. Typically the efficiency drops 2 to 5% when operating away from this optimal point.
Solar cells have an optimal operating voltage. This is the voltage at Maximum Power Point (MPP). The MPP varies according to the sunlight on the panel, the temperature and age of the panel. Modern inverters are provided with a means to control their power output thereby operating their solar cells at the MPP and a means to track and adjust this power level. Temperature sensors to measure the panel temperature and control the panel voltage accordingly have also been used.
The present invention relates to a system for converting the DC power generated from solar panels to AC power. The system is aimed at providing greater efficiency and a number of other advantages, including control of the panel voltage in a manner that will allow each panel to operate near its maximum power point and a means to safely shutdown the system for maintenance.